Isocyanate-based polymer foam and process for production thereof

ABSTRACT

An isocyanate-based polymer foam comprising an isocyanate-based polymer foam matrix having disposed therein a particulate material having an enthalpy of endothermic phase transition of at least about 50 J/g. A process for producing the foam is also described. During the process, the particulate material acts as a heat sink and will undergo an endothermic phase change by absorbing a significant portion of the heat of reaction liberated during the process. This improves the safety of the process by lowering the maximum exotherm experienced by the foam and/or improves product properties.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The press invention relates to an isocyanate-based polymer foamand to a process for production hereof. More particularly, the presentinvention relates to a novel manner of mitigating the exothermexperienced by an isocyanate-based polymer foam during production.

[0003] 2. Description of the Prior Art

[0004] Isocyanate-based polymers are known in the art. Generally, thoseof skill in the art understand isocyanate-based polymers to bepolyurethanes, polyureas, polyisocyanurates and mixtures thereof.

[0005] It is also known in the art to produce foamed isocyanate-basedpolymers. Indeed, one of the advantages of isocyanate-based polymerscompared to other polymer systems is that polymerization and foaming canoccur in situ. This results in the ability to mold the polymer while itis forming and expanding.

[0006] Generally, an isocyanate-based polymer foam may be produced byreaction a mixture comprising an isocyanate, an activehydrogen-containing compound (i.e., a polyol in the case ofpolyurethane, a polyamine in the case of polyurea, etc.), a blowingagent, a catalyst and one or more other optional ingredients (e.g.,fillers, surfactants, chain extending agents, cell openers, and thelike).

[0007] One of the conventional ways to produce a polyurethane foam isknown as the “one-shot” technique. In this technique, the isocyanate, asuitable polyol, a catalyst, water (which acts as a reactive “blowing”agent and can optionally be supplemented with one or more auxiliaryblowing agents) and other additives are mixed together at once using,for example, impingement mixing (e.g., high pressure). Generally, if onewere to produce a polyurea, the polyol would be replaced with a suitablepolyamine. A polyisocyanurate may result from cyclotrimerization of theisocyanate component. Urethane-modified polyureas or polyisocyanuratesare known in the art. In either scenario, the reactants would beintimately mixed very quickly using a suitable mixing technique.

[0008] Another technique for producing foamed isocyanate-based polymersis known as the “prepolymer” technique. In this technique, a prepolymeris produced by reacting polyol and isocyanate (in the case of apolyurethane) in an inert atmosphere to form a liquid polymer terminatedwith reactive groups (e.g., isocyanates). To produce the foamed polymer,the prepolymer is thoroughly mixed with a lower molecular weight polyol(in the case of producing a polyurethane) or a polyamine (in the case ofproducing a modified polyurea) in the presence of a curing agent andother additives, as needed.

[0009] The two major categories of isocyanate-based polymer foams aremolded foams and slabstock foams.

[0010] Generally, molded foams are produced by dispensing a foamablecomposition into a mold cavity, closing the mold to define a cavityhaving the desired shape of the article being produced and allowing thefoamable composition to polymerize and expand thereby filling the moldcavity.

[0011] Generally, slabstock foams are produced as large buns using acontinuous or semi-continuous process. These processes usually involvedispensing the foamable composition into a trough having a open top,side walls and a moving bottom conveyer which serves to translate thefoaming mass away from the dispensing point. The product here istypically a foam bun. The bun can be 100 feet long with across-sectional face of up to 7 feet by 4 feet.

[0012] Not surprisingly, when producing slabstock foam the exotherm ofthe foam is a significant safety concern. As is known in the art, thereaction between isocyanate and polyol (i.e., when producing apolyurethane foam) is exothermic liberating a significantly large amountof heat. While the exotherm in a molded foam is manageable because thesize of the volume product is relatively small, the exotherm inslabstock foam must be specifically addressed since the product is solarge. As used throughout this specification, the term “exotherm”, whenused in the context of an isocyanate-based polymer foam, is intended tomean heat of reaction experienced by the foam during production. Thus,the term, “maximum exotherm” is intended to the mean the maximum heat ofreaction experienced by the foam during production—practically, this maybe assessed by measuring the maximum temperature reached the foam(typically in the area of the core) directly after production. Inpractice, once a threshold temperature is reached (typically 165°C.-175° C. for most open cell slabstock foams and up to 200° C. for mostrigid, semi-rigid and low airflow slabstock foams), in the presence ofair or oxygen, auto-oxidation of the foam may occur resulting indiscoloration (product deterioration) and sometimes fire (damagingand/or destroying the manufacturing facility).

[0013] The prior art as attempted to address this exotherm problem inslabstock foams using a number of approaches.

[0014] One approach relates to replacement of water as an indirectblowing agent with liquid organic blowing agents having a higher heatcapacity—i.e., the liquid organic blowing agent would absorb at least aportion of the liberated heat of reaction. Examples of liquidhydrocarbon blowing agents useful for this purpose include:chlorofluorocarbons (e.g., Freon-11, Freon-12, etc.),chlorofluorohydrocarbons (e.g., Freon-142b, Freon-22, etc.), methylenechloride, acetone, 1,1,1-trichloroethane and the like. One problem withthis approach is environmental. Specifically in the mid-1980's, variousgovernment agencies began to scrutinize the use of organic carbon-basedcompounds such as hydrocarbon-based and halocarbon-based blowing agentsin light of studies which revealed the potential damage caused by escapeof such compounds to and interaction with the ozone layer surroundingthe Earth. As a result, the governments of many countries in the worldhave instituted legislation which significantly curtails or evenprohibits the use of organic carbon-based blowing agents such ashydrocarbon-based and halocarbon-based blowing agents.

[0015] Another approach involves the use of liquid carbon dioxide toreplace the carbon dioxide produced in-situ during the reaction betweenthe isocyanate and water. A disadvantage of this approach is that itnecessitates significantly high capital cost in the manufacturingfacility and there are processing problems (e.g., “pin-holes” in theproduct and/or poor flow characteristics before rise) with the product.

[0016] Yet another approach involves trying to rapidly cool a fresh,“hot” bun of foam by drawing cold or ambient air through the bun. Adisadvantage of this approach is that the properties of the foam must betightly controlled to ensure that it has a high open cell content toallowing the airflow to pass through the foam.

[0017] Yet another approach involves the use a reduced atmosphericpressure to produced low density foam without an excessive amount ofwater. A disadvantage of this approach is that it necessitatessignicantly high capital cost in the manufacturing facility and the useof relatively expensive copolymer polyols to achieve the firmness of thefoam which would ordinarily be lost by reducing the amount of water inthe foam formulation.

[0018] Thus, despite these various prior art approaches there remains aneed in the art for a reliable way of reducing the exotherm inherent inthe production of isocyanate-based foams, particulary slabstockpolyurethane foams. It would be even more advantageous if the exotherminherent in the production of the isoyanate-based foam could be reducedwithout the necessitating an increase in the capital cost of themanufacturing facility and/or the use of relatively expensive chemicalsin the foam formulation.

SUMMARY OF THE INVENTION

[0019] It is an object of the invention to obviate or mitigate at leastone of the above-disadvantages of the prior art.

[0020] It is another object of the invention to provide a novelisocyanate-based polymer foam.

[0021] It is yet anoter object of the present invention to provide anovel process for producing an isocyanate-based polymer foam.

[0022] Accordingly, in one of its aspects, the present inventionprovides an isocyanate-based polymer foam comprising an isocyanate-basedpolymer foam matrix having disposed therein a particulate materialhaving an enthalpy of endothermic phase transition of at least about 50J/g.

[0023] Accordingly, in one of its aspects, the present inventionprovides an isocyanate-based polymer foam comprising an isocyanate-basedpolymer foam matrix having disposed therein a crystaline particulatematerial.

[0024] In another of its aspects, the present invention provides aprocess for producing of an isocyanate-based polymer foam, the processcomprising the steps of;

[0025] contacting an isocyanate, an active-hydrogen containing compound,water, a catalyst and a particulate material having an enthalpy ofendothermic phase transition of at least about 50 J/g to produce areaction mixture;

[0026] expanding the reaction mixture to produce the isocyanate-basedpolymer foam.

[0027] In yet another of its aspects, the present invention provides aprocess for producing an isocyanate-based polymer foam, the processcomprising the steps of:

[0028] contacting an isocyanate, an active-hydrogen containing compound,water, a catalyst and a crystalline particulate material to produce areaction mixture;

[0029] expanding the reaction mixture to produce the isocyanate-basedpolymer foam.

[0030] In yet another of its aspects, the present invention provides aprocess for producing an isocyanate-based polymer foam, the processcomprising the steps of:

[0031] contacting an isocyanate, an active-hydrogen containing compound,water, a catalyst and a particulate material to produce a reactionmixture;

[0032] expanding the reaction mixture to produce the isocyanate-basedpolymer foam;

[0033] wherein the particulate material is selected such that thetemperature of the reacton mixture during expansion is lower than thetemperature of a reaction omitting the particulate material.

[0034] Throughout this specification, the terms “enthalpy of melting”,“latent heat of melting” and “heat of fusion” are intended to have thesame meaning and are used interchangeably, and area encompassed by theenthalpy of endothermic phase transition of the material.

[0035] Thus, the present inventors have discovered a novel approach tothe production of isocyanate-based foams in which the maximum exothermexperienced by the foam during production is reduced thereby improvingproduct properties and, importantly, improving plant safety bymitigating the occurrence of auto-oxidation of the foam. Generally, thediscovery relates to the addition to the foam formulation of an additivematerial which is capable of undergoing a transition involving anendothermic phase change. Typically, the material will be a solid atambient temperature and pressure. While not wishing to be bound by anyparticular theory or mode of action, it is believed that, in most cases,the endothermic phase change will occur by the solid absorbing at leasta significant portion of the heat of reaction liberated duringproduction of the isocyanate-based polymer foam resulting in meltingand/or endothermic transition (e.g., sublimation) of the solid material.As the foam cools the additive material may solidify. Thus, while it isbelieved that the total heat of reaction in production of the foamremains substantially unchanged, the additive material is believed toact as an active heat sink (i.e., the material is active in the sensethat it undergoes some form of phase transition before the maximumexotherm of the foam) which quickly absorbs a portion of the heat ofreaction and subsequently liberates the absorbed heat of reaction over arelatively long period of time. The net result of this a lowering of themaximum exotherm (or temperature) experienced by the foam duringproduction and possibly, as side benefit, more uniform and/or improvedpoperties (e.g., deceased humid-aged compression set) due to a reductionin the temperature gradient experienced by the foam.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Embodiments of the present invention will be described withreference to the accompanying drawings, in which;

[0037] FIGS. 1-6 illustrate the results of Differential ScanningCalorimetry (DSC), pursuant to ASTM E793-85, conducted in respect ofvarious particulate materials;

[0038] FIGS. 7-9 illustrate the exothem profiles for various foams madein the Examples set out hereinbelow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The present invention is related to, inter alia, aisocyanate-based polymer foam comprising a particulate material and to aprocess for production thereof.

[0040] Generally, the present isocyanate-based polymer foam is selectedfrom the group comprising polyurethane foam, polyurea foam,polyisocyanurate foam, urea-modified polyurethane foam,urethane-modified polyurea foam, urethane-modified polyisocyanurate foamand urea-modified polyisocyanurate foam. The preferred foamedisocyanate-based polymer is selected from the group consisting ofpolyurethane foam and urea-modified polyurethane foam. The mostpreferred isocyanate-based polymer is polyurethane foam. As is known inthe art, the term “modified”, when used in conjunction with apolyurethane, polyurea or polyisocyanurate means that up to 50% of thepolymer backbone forming linkages have been substituted.

[0041] In one preferred embodiment, the particulate material has anenthalpy of endothermic phase transition of at least about 50 J/g.Preferably the particulate material has an enthalpy of endothermic phasetransition in the range of about 50 to about 600 J/g, more preferablyfrom about 75 to about 400 J/g, most preferably from about 100 to about250 J/g. For a given particulate material, the enthalpy of endothermicphase transition can be readily determined by a person of ordinary skillin the art. Specifically, the test method for Heats of Fusion andCrystallization may be determined by Differential Scanning Calorimetry(DSC)), pursuant to ASTM E793-85.

[0042] The particulate material should be chosen such that it canundergo a transition involving an endothermic phase change (i.e., aphase change as a result of absorbing heat) at a temperature below themaximum exotherm which the foam would experience during production inthe absence of the particulate material. The maximum exotherm may bedetermined as follows:

[0043] 1. The foamable composition (typically comprising an isocyanate,an active-hydrogen containing compound, water, a catalyst and aparticulate material) is poured into a container.

[0044] 2. Immediately after the foam has reached the full rise, athermocouple probe is inserted into the geometric centre of the bun.When the thermocouple reaches the centre of the bun is considered astime zero and the first reading is taken.

[0045] 3. Temperature readings are taken every minute, while temperaturewas rising, and every 15 minutes after the maximum was reached until adecrease of 20° C. is reached.

[0046] A flexible thermocouple probe of diameter 1-2 mm is preferred.The length of the probe should be sufficient to reach the centre of thebun. Actual measurements can be done by using, for example, thermocoupleAFDO/240GK03H with a Gordon sensor 0.063″ diameter and 24″ long sheathfrom Zesta Engineering Ltd. A type K thermocouple digital thermometerfrom Barnat Company can be used for the temperature readings.

[0047] Preferably, the particulate material is a solid at ambienttemperature and pressure (e.g., 20° C. and 1 atmosphere, respectively).Ideally, the physical transition occurs as a result of the particulatematerial absorbing at least a portion of the heat of reaction from thereaction mixture thereby resulting in at least one of melting,dehydration, sublimation and solid/solid transition, preferably melting,of the particulate material.

[0048] The particulate material may be crystalline or non-crystalline.Highly crystalline polymers and/or partially crystalline(semi-crystalline) polymers are specifically preferred for use as theparticulate materials.

[0049] The size of the particulate material is not specificallyrestricted provided that it does not have a deleterious effect onprocessing of the (e.g., the size of the particulate material should notresult in such an increase in viscosity of the resin that it becomesdifficult to meter or otherwise handle). Preferably, the particulatematerial has an average particle size of less than about 1000 μm, morepreferably in the range of from about 1 to about 500 μm, most preferablyin the range of from about 10 to about 200 μm.

[0050] The amount of particulate material contain is in the presentisocyanate-based polymer foam is preferably less than about 20% byweight of the foam, more preferably from about 0.5% to about 15% byweight of the foam, most preferably from about 5% to about 10% by weightof the foam. The amount of particulate material used can be influencedby a number of factors, including the heat capacity of the specificparticulate material being used, the maximum exotherm of the foam beingproduced with the particulate material and the viscosity of thereaction, especially at higher loadings of particulate material.

[0051] As described above, the preferred particulate material iscrystalline in nature. In this regard, it should be appreciated that theterm “crystalline”, when used in this specification in reference to theparticulate material, is intended to have a broad meaning and coverspartially crystalline (i.e., semi-crystalline) and high crystallinesolids. Such particulate materials are especially useful to producemolded foam or a slabstock foam. However, as will be plainly apparent toa person skilled in the art, the present process may be usedadvantageously to lower the maximum exotherm of a slabstock foam duringproduction. While not wishing to be bound by any particular theory ormode of action, it is believed that at least some of the advantagesaccruing from the present invention relate to the heat absorptioncapability of the crystalline particulate material. Specifically, inthis preferred embodiment, the crystalline a particulate material isused which has a melting below the maximum temperature reached by thefoam during production (this may be determined as discussed above).Thus, as heat is liberated during the reaction, a portion thereof,instead of raising the exotherm of the foam, is absorbed by thecrystalline particulate material, typically resulting in melting of theparticulate material. Since the crystalline particulate material issubstantially uniformly distributed throughout the foam matrix, theresult is an overall lowering of the maximum exotherm experienced by thefoam. This dramatically improves the safety of foam production and/orobviates deterioration of production properties. As the foam matrixcools after production, the particulate material re-crystallizes orre-solidifies.

[0052] In one preferred embodiment, the particulate material is organic,preferably an organic polymer, more preferably a thermoplastic material.Non-limiting examples of useful thermoplastic polymers may be selectedfrom the group comprising: polyethylene, polypropylene, chlorinatedpolyethylene, ethylene-vinyl-acetate (EVA) polyethylethacrylate (PEEA),acetal, nylon 11, polyvinylidenechloride, polybutene,epichlorohydrin(ECO) plastic rubber-modified analogues copolymers andmixtures thereof. More preferably, the particulate material is selectedfrom the group comprising polyethylene, polypropylene and mixturesthereof. Most preferably, the particulate material is crystallinepolyethylene. Non-limiting examples of other useful organic materialsmay be selected from the group comprising paraffins, fatty acids,alcohols, tetradecanoic acid mysistamide, salts of fatty acids (e.g.,calcium stearate (melting point 180° C.), zinc stearate (melting point130° C.), zinc laurate (melting point 130° C.) and the like).

[0053] Alternatively, the particulate material may be inorganic.Non-limiting examples of other useful organic materials may be selectedfrom the group comprising sodium thiosulfate pentahydrate (melting point75° C.), sodium acetate trihydrate (melting point 58° C.), sodiumsulfate decahydrate (melting point 32° C.), sodium carbonate(dehydration point 100° C.), barium hydroxide (melting point 78° C.),calcium chloride (dehydration point 100° C.), nickel nitratetetrahydrate (melting point 40° C.), zinc nitrate hexahydrate (meltingpoint 36.4-45.5° C.), blends thereof, alloys thereof and eutecticmixtures thereof.

[0054] Of course, those of skill in the art will recognize that modifiedparticulate materials may also be used. For example, it is known tosurface modify particles by exposing them to ultraviolet, electrobeamand similar treatments to, for example, improve adhesion of theparticles in the matrix in which there are being dispersed.

[0055] A preferred process for producing the present isocyanate-basedpolymer foam comprises the steps of:

[0056] contacting an isocyanate, an active-hydrogen containing compound,water, a catalyst and a particulate material to produce a reactionmixture;

[0057] expanding the reaction mixture to produce the isocyanate-basedpolymer foam.

[0058] The first step in the present process comprises provision of areaction mixture comprising an active hydrogen-containing compound, anisocyanate, an aqueous blowing agent and a catalyst.

[0059] Preferably, the active hydrogen-containing compound is selectedfrom the group comprising non-hydrophilic polyols, polyamines,polyamides, polyimines, polyolamines and mixtures thereof.

[0060] Thus, if the process is utilized to produce a polyurethane foam,the active hydrogen-containing compound is typically a polyol.Generally, the choice of such a polyol is not particularly restrictedand is within the purview of a person skilled in the art. For example,the polyol may be a hydroxyl-terminated compound selected from the groupcomprising polyether, polyester, polycarbonate, polydiene andpolycaprolactone. The polyol may be selected from the group comprisinghydroxyl-terminated polyhydrocarbons, hydroxyl-terminated polyformals,fatty acid triglycerides, hydroxyl-terminated polyesters,hydroxymethyl-terminated polyesters, hydroxymethyl-terminatedperfluoromethylenes, polyalkylene ether glycols,polyalkylenearyleneether glycols and polyalkyleneether triols. Thepolyol may also be selected from the group comprising adipicacid-ethylene glycol polyester, poly(butylene glycol), poly(propyleneglycol) and hydroxyl-terminated polybutadiene—see, for example, Britishpatent No. 1,482,213, the contents of which are incorporated herein byreference. Blends of one or more of such polyols are also possible.Preferably, such a polyol has a molecular weight in the range of fromabout 200 to about 20,000, most preferably from about 300 to about6,000.

[0061] Further, it is possible to utilize a prepolymer technique toproduce a polyurethane foam within the scope of the present invention.In one embodiment, it is contemplated that the prepolymer be prepared byreacting an excess of isocyanate with a polyol (as discussed above). Theprepolymer could then be reacted with further polyol (the same ordifferent than the first polyol) to produce a polyurethane foam or anamine to produce a polyurea-modified polyurethane.

[0062] If the process is utilized to produce a polyurea-modifiedpolyurethane foam, the hydrogen-containing compound comprises, at leastin part, compounds wherein hydrogen is bonded to nitrogen. Preferablysuch compounds are selected from the group comprising polyamines,polyamides, polyimines and polyolamines, more preferably polyamines.Non-limiting examples of such compounds include primary and secondaryamine terminated polyethers. Preferably such polyethers have a molecularweight of greater than about 1500, a functionality of from 2 to 6, andan amine equivalent weight of from about 200 to about 6,000. Such amineterminated polyethers are typically made from an appropriate initiatorto which a lower alkylene (e.g., ethylene, propylene, butylene andmixtures thereof) oxide is added with the resulting hydroxyl terminatedpolyol being subsequently aminated. If two or more alkylene oxides areused, they may be present either as random mixtures or as blocks of oneor the other polyether. For ease of amination, it is especiallypreferred that the hydroxyl groups of the polyol be essentially allsecondary hydroxyl groups. Typically, the amination step replaces themajority but not all of the hydroxyl groups of the polyol.

[0063] In another embodiment, the first polyol may comprise a polymerpolyol, also known as graft copolymer polyols. As is known in the art,such polyols are generally polyether polyol dispersions which are filledwith other organic polymers. Such polymer polyols are useful in loadbuilding or improving the hardness of the foam when compared to usingunmodified polyols. Non-limiting examples of useful polymer polyolsinclude: chain-growth copolymer polyols (e.g., containing particulatepoly(acrylonitrile), poly(styrene-acrylonitrile) and mixtures thereof),and/or step-growth copolymer polyols (e.g., PolyHarnstoff Dispersions(PHD), polyisocyanate polyaddition (PIPA) polyols, epoxy dispersionpolyols and mixtures thereof). For further information on polymerpolyols, see, for example, Chapter 2 of FLEXIBLE FOAM FUNDAMENTALS,Herrington et al. (1991) and the references cited therein, the contentsof which are incorporated herein by reference. If a polymer polyol isused, it may be present alone or in admixture with an unmodified polyol.Generally, mixtures may be used which contain polymer polyol in anamount in the range of from about 5 to about 100 percent by weight ofunmodified polyol present in the mixture.

[0064] As used throughout this specification, the term “equivalentweight” means mass of active hydrogen-containing compound per reactivehydrogen pursuant to the following formula:

Equivalent Weight=M.W./f

[0065] wherein M.W. is the molecular weight of the compound and f is thenumber of reactive hydrogens (i.e. functionality) in a molecule of thecompound. Thus, one equivalent weight of active hydrogen-containingcompound will react stoichiometrically with one equivalent weight ofisocyanate.

[0066] Since determining the functionality of the polyol can be complex,an alternative and practical way to determine the equivalent weight of apolyol is pursuant to the following equation:

Equivalent Weight=(56.1×1000)/OH Number

[0067] wherein OH Number is the hydroxyl number of the polyol. As isknown in the art, hydroxyl number can be measured and provides anindication of the number of hydroxyl groups in the polyol which areavailable for reaction. As is further known in the art, there arevarious conventional analytical methods for determining the hydroxylnumber of a polyol—see, for example, Chapter 2 of FLEXIBLE FOAMFUNDAMENTALS, Herrington et al. (1991) and the references cited therein,the contents of which are incorporated herein by reference. Theseanalytical methods include wet analytical and infrared spectroscopictechniques.

[0068] The reaction mixture in the first step of the present processfurther comprises an isocyanate. Of course, those of skill in the artwill recognize that a mixture of two or more isocyanates may be used.The choice of isocyanate suitable for use in the reaction mixture isgenerally within the purview of a person skilled in the art. Generally,the isocyanate compound suitable for use may be represented by thegeneral formula:

Q(NCO)_(i)

[0069] wherein i is an integer of two or more and Q is an organicradical having the valence of i. Q may be a substituted or unsubstitutedhydrocarbon group (e.g. an alkylene or arylene group). Moreover, Q maybe represented by the general formula:

Q¹—Z—Q¹

[0070] wherein Q¹ is an alkylene or arylene group and Z is chosen fromthe group comprising —O—, —O—Q¹—, —CO—, —S—, —S—Q¹—S— and —SO₂—.Examples of isocyanate compounds which fall within the scope of thisdefinition include hexamethylene diisocyanate,1,8-diisocyanato-p-methane, xylyl diisocyanate, (OCNCH₂CH₂CH₂OCH₂O)₂,1-methyl-2,4-diisocyanatocyclohexane, phenylene diisocyanates, toluenediisocyanates, chlorophenylene diisocyanates,diphenylmethane-4,4′-diisocyanate,naphthalene-1,5-diisocyanatetriphenylmethane-4,4′,4′-triisocyanateand isopropylbenzene-alpha-4-diisocyanate.

[0071] In a preferred embodiment, Q may also represent a polyurethaneradical having a valence of i. In this case Q(NCO)_(i) is a compoundwhich is commonly referred to in the art as a prepolymer. Generally, aprepolymer may be prepared by reacting a stoichiometric excess of anisocyanate compound (as discussed hereinabove) with apolyhydroxyl-containing material or polyol (as discussed hereinabove).In this embodiment, the isocyanate may be, for example, used inproportions of from about 30 percent to about 200 percent stoichiometricexcess with respect to the proportion of hydroxyl in the polyol. Theprepolymer may then be reacted with a polyol to produce a polyurethanefoam or an amine to produce a polyurea-modified polyurethane. As will bedemonstrated below, if the polyol used to produce the prepolymer is thechain extending agent (as discussed hereinbelow), it is still necessaryto utilize the second polyol in the polyol mixture. Further, the secondpolyol in the polyol mixture described above should be used in thepolyol mixture regardless of whether a similar polyol is used to producethe prepolymer to ensure that a polyurethane foam having an integralskin is produced. Thus, in the context of the present process, aprepolymer should be considered a subset of useful isocyanates and theuse thereof does not replace the need to use the polyol mixturediscussed hereinabove. A non-limiting example of a prepolymer useful inthe present process is commercially available from Bayer Corporationunder the tradename Mondur™ PF.

[0072] In another embodiment, the isocyanate compound suitable for usein the process of the present invention may be selected from dimers andtrimers of isocyanates and diisocyanates, and from polymericdiisocyanates having the general formula:

[Q″(NCO)_(i)]_(j)

[0073] wherein both i and j are integers having a value of 2 or more,and Q″ is a polyfunctional organic radical, and/or, as additionalcomponents in the reaction mixture, compounds having the generalformula:

L(NCO)_(i)

[0074] wherein i is an integer having a value of 1 or more and L is amonofunctional or polyfunctional atom or radical. Examples of isocyanatecompounds which fall with the scope of this definition includeethylphosphonic diisocyanate, phenylphosphonic diisocyanate, compoundswhich contain a ═Si—NCO group, isocyanate compounds derived fromsulfonamides (QSO₂NCO), cyanic acid and thiocyanic acid.

[0075] See also for example, British patent No. 1,453,258, the contentsof which are incorporated herein by reference.

[0076] Non-limiting examples of suitable isocyanates include:1,6-hexamethylene diisocyanate, 1,4-butylenediisocyanate,furfurylidenediisocyanate, 2,4-toluene diisocyanate, 2,6-toluenediisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethanediisocyanate, 4,4′-diphenylpropane diisocyanate,4,4′-diphenyl-3,3′-dimethyl methane diisocyanate, 1,5-naphthalenediisocyanate,1-methyl-2,4-diisocyanate-5-chlorobenzene2,4-diisocyanato-s-triazine,1-methyl-2,4-diisocyanato cyclohexane, p-phenylene diisocyanate,m-phenylenediisocyanate, 1,4-naphthalene diisocyanate, dianisidinediisocyanate, bitoluene diisocyanate, 1,4-xylylene diisocyanate,1,3-xylylene diisocyanate, bis-(4-isocyanatophenyl)methane,bis-(3-methyl-4-isocyanatophenyl)methane, polymethylene polyphenylpolyisocyanates and mixtures thereof.

[0077] A preferred isocyanate is selected from the group comprising2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate andmixtures thereof. A preferred isocyanate of this type is a mixturecomprising from about 15 to about 25 percent by weight2,4′-diphenylmethane diisocyanate and from about 75 to about 85 percentby weight 4,4′-diphenylmethane diisocyanate. An example of such anisocyanate is commercially available from Imperial Chemical Industriesunder the tradename Rubinate M. Another preferred isocyanate of thistype is commercially available from BASF Corporation under the tradenameLupranate™ MM-103 (a solvent-free, carbodiimide modified4,4′-diphenylmethane diisocyanate).

[0078] Another preferred isocyanate may be selected from the groupcomprising 2,4-toluene diisocyanate, 2,6-toluene diisocyanate andmixtures thereof.

[0079] Preferably, the isocyanate used in the present process has afunctionality in the range of from about 2.0 to about 2.7.

[0080] The isocyanate preferably is used in an amount to provide anisocyanate index, inclusive of all reactive equivalents in the reactionmixture, in the range of from about 60 to about 200, more preferablyfrom about 70 to about 140, most preferably from about 90 to about 120.

[0081] The reaction mixture used in the first step of the presentprocess further comprises a blowing agent. The preferred blowing agentis aqueous blowing agent. As is known in the art, aqueous blowingagents, such as water, can be used as a reactive blowing agent in theproduction of isocyanate-based polymer foams. Specifically, water reactswith the isocyanate forming carbon dioxide which acts as the effectiveblowing agent in the final foamed polymer product. A key advantage ofthe present process is the ability to produce a slabstock polyurethanefoam using an amount of water which, in conventional practice, couldresults in a very high exotherm in the foam after production.

[0082] It is known in the art that the amount of water used as a blowingagent in the preparation of a isocyanate-based polymer foam isconventionally in the range of from about 0.20 to as high as about 8.0or more parts by weight, most preferably from about 2.5 to about 8.0parts by weight, per one hundred parts by weight of the activehydrogen-containing compound in the reaction mixture. Since the amountof water used in the production of a foam is limited by the fixedproperties expected or desired in the foam, it may be desirable, incertain circumstances, to utilize a substantially inert liquid extenderif a highly filled (e.g., pigmented) foam is being produced.Non-limiting examples of suitable liquid extenders include halogenatedhydrocarbons, high molecular weight hydrocarbons and polyols.

[0083] The reaction mixture used in the first step of the presentprocess further comprises a catalyst. The catalyst promotes reaction ofthe polyol mixture with the isocyanate. The choice and use of such acatalyst is within the purview of a person skilled in the art. See forexample U.S. Pat. Nos. 4,296,213 and 4,518,778, the contents of each ofwhich is incorporated herein by reference. Suitable catalysts includetertiary amines and/or organometallic compounds. Non-limited examples ofuseful catalysts for use in the present process may be selected from thegroup consisting of quaternary ammonium salts, triethylenediamine,N-methylmorpholine, N-ethylmorpholine, diethanolamine, N-cocomorpholine,1-methyl-4-dimethylaminoethylpiperazine, methoxypropyldimethylamine,N,N,N′-trimethylisopropyl propylenediamine,3,-diethylaminopropyldiethylamine, dimethylbenzylamine, dibutyltindilaurate, dibutyltindiacetate, stannous chloride, dibutyltin di-2-ethylhexanoate, stannous octoate and mixtures thereof. See, for example, U.S.Pat. No. 4,590,219 [Nissen et al.], the contents of which are herebyincorporated by reference, for a discussion of various of these andother suitable catalysts. Preferably, the catalyst is used in an amountin the range of from about 0.05 to about 2.5, more preferably from about0.10 to about 2.0, most preferably from about 0.10 to about 0.60, partsby weight per one hundred parts by weight of the polyol mixture.

[0084] As will be clearly understood by those of skill in the art, it iscontemplated that conventional additives in the polyurethane foam artcan be used in the present process. Non-limiting examples of suchadditives include: filler materials (e.g., materials which have anenthalpy of endothermic transition less than 50 J/g), surfactants (e.g.,organo-silicone compounds available under the tradename L-540 UnionCarbide), cell openers (e.g., silicone oils), extenders (e.g.,halogenated paraffins commercially available as Cereclor S45),cross-linkers (e.g., low molecular weight reactive hydrogen-containingcompositions), pigments/dyes, flame retardants (e.g., halogenatedorgano-phosphoric acid compounds), inhibitors (e.g., weak acids),nucleating agents (e.g., diazo compounds), anti-oxidants, UV stabilizers(e.g., hydroxybenzotriazoles, zinc dibutyl thiocarbamate, 2,6-ditertiarybutylcatechol, hydroxybenzophenones, hindered amines and mixturesthereof), plasticizers (e.g., sulfonated aromatic compounds), biocides,antistatic agents (e.g., ionizable metal salts, carboxylic acid salts,phosphate esters and mixtures thereof) and mixtures thereof. The amountsof these additives conventionally used is within the purview of a personskilled in the art—see, for example, Chapter 2 of FLEXIBLE FOAMFUNDAMENTALS, Herrington et al. (1991) and the references cited therein,the contents of which are incorporated herein by reference.

[0085] The manner by which the polyol mixture, isocyanate, blowingagent, particulate material and catalyst are contacted in the first stepof the present process is not particularly restricted. Thus, it ispossible to preblend the components in a separate tank which is thenconnected to a suitable mixing device for mixing with the blowing agentand catalyst. Alternatively, it is possible to preblend the activehydrogen-containing compound with the blowing agent, catalyst and otheradditives, if present, to form a resin. This resin preblend could thenbe fed to a suitable mixhead (high pressure or low pressure) which wouldalso receive an independent stream of the isocyanate.

[0086] Once the active hydrogen-containing compound, isocyanate, blowingagent, chain extending agent and catalyst have been contacted and,ideally, mixed uniformly, a reaction mixture is formed. This reactionmixture is then expanded to produce the present isocyanate-basedpolyurethane foam. As will be apparent to those of skill in the art, theprocess of the present invention is useful in the production ofslabstock foam, molded articles and the like. The manner by whichexpansion of the reaction mixture is effected will be dictated by thetype of foam being produced.

[0087] Embodiments of the present invention will now be described withreference to the following Examples which should not be construed aslimiting the scope of the invention. The term “pbw” used in the Examplesrefers to parts by weight.

[0088] In the Examples the following compounds were used:

[0089] 1. Arcol™ LHT-112, a polyether polyol having equivalent weight of500 (molecular weight of approximately 1500), commercially availablefrom Lyondell Corporation;

[0090] 2. Arcol™ F-3020, a polyether polyol having equivalent weight of1000 (molecular weight of approximately 3000), commercially availablefrom Lyondell Corporation;

[0091] 3. Arcol™ E788, a polyether polyol having about 38% SAN solids,equivalent weight of 2540, commercially available from LyondellCorporation;

[0092] 4. Arcol™ PPG-725, a polyether polyol having equivalent weight of380 (molecular weight of approximately 760), commercially available fromLyondell Corporation;

[0093] 5. Voranol™ 360, a polyether polyol having equivalent weight of156 (molecular weight of approximately 700), commercially available fromThe Dow Chemical Company;

[0094] 6. Voranol™ 230-660, a polyether polyol having equivalent weightof 85 (molecular weight of approximately 250), commercially availablefrom The Dow Chemical Company;

[0095] 7. Baynat-755™, a polyether polyol system having equivalentweight of 150-168 and water content of 4.2-4.4 pph, commerciallyavailable from Bayer Corporation;

[0096] 8. PS 2502A, a polyester polyol having an equivalent weight of224.4, commercially available from Stepan Corporation;

[0097] 9. Pluracol™ 1178, a polyether polyol having equivalent weight of2250 (molecular weight of 6500), commercially available from BASFCorporation;

[0098] 10. Voranol™ V4701, a polyether polyol having an equivalentweight of 1780 (molecular weight approx. 5340), commercially availablefrom The Dow Chemical Company;

[0099] 11. DEOA-LF, diethanolamine—low freezing grade, having 15% water,an equivalent weight of 24, commercially available from The Dow ChemicalCompany;

[0100] 12. Tegostab™ B8871, an organosilicone copolymer cell-openingsurfactant commercially available from Goldschmidt Chemical Corporation;

[0101] 13. Niax™ L5770—alkyl-pendant organosilicone surfactant,commercially available from Osi Specialities, a Witco Company;

[0102] 14. Niax™ Y10184, organosilicone surfactant for molded foams,commercially available from Osi Specialities, A Witco Company;

[0103] 15. Tegostab™ B4690—organosilicone surfactant for moulded foams,commercially available from Goldschmidt Chemical Corporation;

[0104] 16. Niax™ A1-70% bis(2-dimethylethaminoethyl) ether indipropylene glycol, commercially available from Osi Specialities, AWitco Company;

[0105] 17. Niax™ C-255—balanced amine catalyst, commercially availablefrom Osi Specialities, A Witco Company;

[0106] 18. Polycat™ 12—N, Methyl dicyclodclorohexylamine, commerciallyavailable from Air Products and Chemicals Inc.;

[0107] 19. Dabco™ T12, Dibuthyltin dilaurate, commercially availablefrom Air Products and Chemicals Inc.;

[0108] 20. Dabco™ 33LV-335, Triethylene diamine in dipropyleneglycol,commercially available from Air Products and Chemicals Inc.;

[0109] 21. Dabco™ T10, stannous octoate, commercially available from AirProducts and Chemicals Inc.;

[0110] 22. Diethyleneglycol, a chain-extender;

[0111] 23. Isocyanate A: PAPI™ 27 Polymeric MDI, polymethylenepolyphenyl isocyanate, containing 4,4′Methylene bisphenyl isocyanatewith total NCO content 31.0-31.5%, commercially available from The DowChemical Company;

[0112] 24. Isocyanate B: Mondur™ MR Polymeric MDI, polymethylenepolyphenyl isocyanate, containing 4,4′Methylene bisphenyl isocyanatewith total NCO content 31.0-31.5%, commercially available from BayerCorporation;

[0113] 25. Isocyanate C: T-80™, toluene diisocyanate, commerciallyavailable TDI;

[0114] 26. Melamine, a particulate material commercially available fromMelamine Chemicals Inc.

[0115] 27. Polyethylene, Escorene™ HD-8761-27 RBG, a particulatematerial commercially available from Exxon Corporation; and

[0116] 28. Polypropylene, Montel™ 5M 6100, a particulate materialcommercially available from Shell.

EXAMPLES 1-12

[0117] In these Examples, various foams were produced pursuant to theformulations provided in Table 1. The methodology used in each Examplewas as follows.

[0118] A resin mixture was produced by mixing all ingredients except theisocyanate and the particulate material. This resin mixture and theisocyanate were preconditioned to a temperature of 25° C.

[0119] The particulate material was ground, as necessary, such that ithad an average particle size of less than 1000 μm. At this point theparticulate material was added to the resin mixture and mixed well untila substantially homogenous mixture was achieved. Of course those ofskill in the art will recognize that the particulate material could beadded to the isocyanate or could divided in some fraction between theresin mixture and the isocyanate.

[0120] The homogeneous resin mixture (i.e., containing the particulatematerial) was mixed in a suitably sized container and the isocyanate wasadded thereto. After approximately 10 seconds, the reaction mixture inthe container was transferred to a 10″×10″×6″ cardboard box and wasallowed to expand to form a free-rise foam bun. A thermocouple attachedto a recorder was inserted into the middle of the foam bun once thefree-rise foam bun had finished expanding (visually) and the temperaturewas recorded used the overall procedure described above.

[0121] With reference to FIGS. 1 and 2, there is illustrated the DSC formelamine, one of the particulate materials used in these Examples. Withreference to FIGS. 3 and 4, there is illustrated the DSC forpolypropylene, one of the particulate materials used in these Examples.With reference to FIGS. 5 and 6, there is illustrated the DSC forpolyethylene, one of the particulate materials used in these Examples.As can be clearly seen, the DSC for polypropylene and polyethyleneresult in an enthalpy of endothermic transition of 87 (average) and 168(average) J/g, respectively. In contrast, the DSC for methylene isnegligible.

[0122] As can be seen with reference to the exotherm reduction reportedin respect of Examples 1-3 in Table 1, the use of polyethylenesignificantly improves exotherm reduction. Specifically, using the sameamount of polyethylene as melamine resulted in a 12-fold increase inexotherm reduction. The results of Examples 1-3 are illustrated in FIG.7.

[0123] With reference to Examples 4-7, it can be seen that, again, theuse of polyethylene and polypropylene results in a significant benefitin terms of exotherm reduction compared to the use of no particulatematerial or the use of melamine which has a negligible enthalpy ofendothermic phase change. The results in Example 4-7 are illustrated inFIG. 8.

[0124] With reference to Examples 8-10, these Examples illustrate thebeneficial exotherm reduction properties previously seen are also seenin a formulation used to produce a rigid molded foam.

[0125] Further, with reference to Examples 11-13, the benefits ofexotherm reduction using polyethylene are seen in a flexible slab foamformulation. The results in Examples 10-12 are illustrated in FIG. 9.

[0126] Further, with reference to Examples 14 and 15, the benefits ofexotherm reduction using polyethylene are seen in a HR mold foamformulation.

[0127] While the invention has been described hereinabove with referenceto various preferred embodiments and specific Examples, it will beclearly understood by those of skill in the art that modifications toand variations of the preferred embodiments and specific Examples arepossible which do not depart from the spirit and scope of the presentinvention. Accordingly, it is contemplated that such modifications toand variations of the preferred embodiments and specific Examples areencompassed by the invention. TABLE 1 Example 1 2 3 4 5 6 7 Type ofcomposition SRS SRS SRS SRS SRS SRS SRS Total OH number 360 360 360 340340 340 340 Arcol ™ PPG-725 — — —  25  25  25  25 Voranol ™ 360 — — — 75  75  75  75 Baynat ™ 755 100 100 100 — — — — Water — — — 3.8  3.8 3.8  3.8  Melamine  24 — — —  26 — — Polyethylene —  6  24 — —  26 —Polypropylene — — — — — —  26 Tegostab ™ B8871 — — — 1.0  1.0  1.0  1.0 Niax ™ A-1 — — — 0.13 0.13 0.13 0.13 Dabco ™ T-12 — — — 0.02 0.02 0.020.02 Isocyanate A — — — 145 145 145 145 Isocyanate B 140 140 140 — — — —Exotherm reduction,  2  6  24 Control  8  25  18 T, ° C. Example 8 9 1011 12 13 Type of composition RM RM RM FS FS FS Total OH number 380 380380  56  56  56 Voranol ™ 230-660  35  35  35 — — — PS 2502A  35  35  35— — — Pluracol ™ P-1178  30  30  30 — — — Arcol ™ F302O — — — 100 100100 DEG  5  5  5 — — Water 3.4 3.4 3.4 6.0 6.0  6.0 Melamine —  26 — — —— Polyethylene — —  26 — 9.0 18.5 Goldschmidt ™ B4690 0.5 0.5 0.5 — — —Niax ™ C-255 — — — 0.3 0.3  0.3 Polycat ™ 12 1.0 1.0 1.0 — — — Dabco ™T-10 — — — 0.2 0.2  0.2 Isocyanate A 140 140 140 — — — Isocyanate C — ——  76  76  76 Exotherm reduction, Control  1  19 Control  16  27 T, ° C.Example 14 15 Type of composition HR HR Total OH number 49 49 Voranol ™4701 54.7 55.4 Arcol ™ 788 45.3 33.9 DEOLF  1.7  1.7 Water  4.0  4.0UAX-Y10184  1.2  1.2 Polyethylene — 10.7 Niax ™ A-1  0.08  0.08 Dabco ™33LV  0.32  0.32 Isocyanate C 49.6 49.2 Exotherm reduction, T, ° C.Control  8

What is claimed is:
 1. An isocyanate-based polymer foam comprising an isocyanate-based polymer foam matrix having disposed therein a particulate material having an enthalpy of endothermic phase transition of at least about 50 J/g.
 2. The isocyanate-based polymer defined in claim 1, wherein the particulate material has an enthalpy of endothermic phase transition in the range of about 50 to about 600 J/g.
 3. The isocyanate-based polymer defined in claim 1, wherein the particulate material has an enthalpy of endothermic phase transition of from about 100 to about 250 J/g.
 4. The isocyanate-based polymer defined in claim 1, wherein the particulate material is a solid at ambient temperature and pressure.
 5. The isocyanate-based polymer defined in claim 1, wherein the particulate material has an average particle size of less than about 1000 μm.
 6. The isocyanate-based polymer defined in claim 1, wherein the particulate material has an average particle size in the range of from about 10 to about 200 μm.
 7. The isocyanate-based polymer defined in claim 1, wherein the particulate material is present in an amount of less than about 20% by weight of the foam.
 8. The isocyanate-based polymer defined in claim 1, wherein the particulate material is present in an amount of from about 5% to about 10% by weight of the foam.
 9. The isocyanate-based polymer foam defined in claim 1, wherein the particulate material is organic.
 10. The isocyanate-based polymer foam defined in claim 1, wherein the particulate material comprises an organic polymer.
 11. The isocyanate-based polymer foam defined in claim 10, wherein the organic polymer is crystalline.
 12. The isocyanate-based polymer foam defined in claim 10, wherein the organic polymer is a thermnoplastic material.
 13. The isocyanate-based polymer foam defined in claim 12, wherein the thermoplastic material is selected from the group comprising polyethylene, polypropylene, chlorinated polyethylene, ethylene-vinyl-acetate (EVA), polyethylethacrylate (PEEA), acetal, nylon 11, polyvinylidenechloride, polybutene, epichlorohydrin (ECO) plastic, rubber-modified analogues, copolymers and mixtures thereof.
 14. The isocyanate-based polymer foam defined in claim 1, wherein the particulate material is selected from the group comprising polyethylene, polypropylene and mixtures thereof.
 15. The isocyanate-based polymer foam defined in claim 1, wherein the particulate material comprises polyethylene.
 16. An isocyanate-based polymer foam comprising an isocyanate-based polymer foam matrix having disposed therein a crystalline particulate material.
 17. A process for producing of an isocyanate-based polymer foam, the process comprising the steps of: contacting an isocyanate, an active-hydrogen containing compound, water, a catalyst and a particulate material having an enthalpy of endothermic phase transition of at least about 50 J/g to produce a reaction mixture; expanding the reaction mixture to produce the isocyanate-based polymer foam.
 18. The process defined claim 17, wherein the blowing agent comprises water.
 19. The process defined in claim 17, wherein the amount water is used in an amount in the range of from about 0.2 to about 8.0 parts by weight per one hundred parts by weight of the active hydrogen-containing compound.
 20. The process defined in claim 17, wherein the amount water is used in an amount in the range of from about 3.0 to about 8.0 parts by weight per one hundred parts by weight of the active hydrogen-containing compound.
 21. The process defined in claim 17, wherein the isocyanate is selected from the group comprising 1,6-hexamethylene diisocyanate, 1,4-butylene diisocyanate, furfurylidene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenylpropane diisocyanate, 4,4′-diphenyl-3,3′-dimethyl methane diisocyanate, 1,5-naphthalene diisocyanate, 1-methyl-2,4-diisocyanate-5-chlorobenzene, 2,4-diisocyanato-s-triazine, 1-methyl-2,4-diisocyanato cyclohexane, p-phenylene diisocyanate, m-phenylene diisocyanate, 1,4-naphthalene diisocyanate, dianisidine diisocyanate, bitoluene diisocyanate, 1,4-xylylene diisocyanate, 1,3-xylylene diisocyanate, bis-(4-isocyanatophenyl)methane, bis-(3-methyl-4-isocyanatophenyl)methane, polymethylene polyphenyl polyisocyanates and mixtures thereof.
 22. The process defined in claim 17, wherein the isocyanate is selected from the group consisting essentially of 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate and mixtures thereof.
 23. The process defined in claim 17, wherein the isocyanate is selected from the group consisting essentially of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures thereof.
 24. The process defined in claim 17, wherein the isocyanate is used in an amount to provide an isocyanate index in the range of from about 60 to about
 200. 25. The process defined in claim 17, wherein the isocyanate is used in an amount to provide an isocyanate index in the range of from about 90 to about
 120. 26. The process defined in claim 17, wherein the active hydrogen-containing compound is selected from the group comprising polyols, polyamines, polyamides, polyimines, polyolamines and mixtures thereof.
 27. The process defined in claim 17, wherein the polyol is a hydroxyl-terminated backbone of a member selected from the group comprising polyether, polyesters, polycarbonate, polydiene, polycaprolactone and mixtures thereof.
 28. The process defined in claim 17, wherein the polyol is a polyether polyol.
 29. The process defined in claim 28, wherein the polyether polyol has a molecular weight in the range of from about 200 to about 20,000.
 30. A process for producing of an isocyanate-based polymer foam, the process comprising the steps of: contacting an isocyanate, an active-hydrogen containing compound, water, a catalyst and a crystalline particulate material to produce a reaction mixture; expanding the reaction mixture to produce the isocyanate-based polymer foam.
 31. A process for producing of an isocyanate-based polymer foam, the process comprising the steps of: contacting an isocyanate, an active-hydrogen containing compound, water, a catalyst and a particulate material to produce a reaction mixture; expanding the reaction mixture to produce the isocyanate-based polymer foam; wherein the particulate material is selected such that the temperature of the reaction mixture during expansion is lower than the temperature of a reaction omitting the particulate material. 